To strengthen and support the future growth of the public and private sectors, Wang Noi Power Plant is the first and the only power plant of the area of generating capacity and transmission system development of the Lower Central region. The power plant has supported economic infra-structure development bringing prosperity to the region and giving services to expanding suburban areas.

Wang Noi Power Plant is an urgent project proposed by the National Economic and Social Development Council. The cabinet acknowledged the approval of environmental process on July 12, 1994. Wang Noi District in Phra Nakhon Si Ayutthaya Province is selected to be the site of Wang Noi Power Plant as it is a potential area being near fuel source, water source and transmission system including the center of electricity demand such as Bangkok Metropolitan Region. This site selection can reduce the cost, power loss in the distribution system, using natural gas from the Gulf of Thailand via the gas pipeline (Bang Pakong-Wang Noi  about 100 km) and from Myanmar.

The construction of Wang Noi Blocks 1-3 began in November, 1994 and completed on April 28, 1998. The opening ceremony of Wang Noi Power plant was inaugurated by His Royal Highness Crown Prince Maha Vajiralongkorn on August 7, 1998.

Later, the rapid economic and industrial growth has resulted in the rising demand for electricity in the Central part of the country, EGAT therefore has prepared for the new power source to strengthen security of the electricity system and to be in line with Power Development Plan – PDP 2010. Wang Noi Power Plant Block 4 was constructed at the former site of Wang Noi Power Plant in December 2011 and completed on April 7, 2014. After the construction, the power plant, Block 4 could supply electricity to the system in May 2014.

At present, Wang Noi Power Plant has the contractual generating capacity of 1,436 MW

• Block 3 with generating capacity of 686 MW
• Block 4 with generating capacity of 750 MW